Question: Complete the equation of the line through $(-9,-9)$ and $(-6,0)$. Use exact numbers. $y=$
Answer: Let's find the slope: $\begin{aligned} \text{Slope}&=\dfrac{0-(-9)}{-6-(-9)} \\\\ &=\dfrac{9}{3} \\\\ &=3 \end{aligned}$ The equation is $y=3x+b$ for some $b$. Let's plug the point $({-6},{0})$ to find $b$ : $\begin{aligned} y&=3 x+b \\\\ {0}&=3({-6})+b \\\\ 0&=-18+b \\\\ 18&=b \end{aligned}$ The equation is $y=3x +18$.